手写call bind apply

Function.prototype.myCall = function(o,...args){
  let content = (o===null||o===undefined)?window:o
  content._fun = this
  let result = content._fun(args)
  delete content._fun
  return result
}
Function.prototype.myBind = function(o){
  let content = (o===null||o===undefined)?window:o
  content._fun = this
  return function(...args){
    content._fun(args)
    delete content._fun
  }()
}
Function.prototype.myApply = function(o,args){
  let content = (o===null||o===undefined)?window:o
  content._fun = this
  let result = content._fun(...args)
  delete content._fun
  return result
}